1. Field of the Invention
This invention relates to container handling apparatus and more particularly to mechanisms for use in inspecting containers on a production line. More particularly, the invention relates to a mechanism for stopping movement of a container on a conveyor so that it may be inspected.
2. Description of the Prior Art
During manufacture, it is necessary to inspect the containers for defects, satisfactory code markings, and the like, so as to make certain that a product of the desired quality is being produced and it is most convenient if the inspection can be carried out without hand manipulation. In some cases only the sides and top of a container need be inspected, and in others the bottom must also be seen. In the first instance, it may not be necessary to remove the container from the conveyor belt on which it is being moved from one point to another during the production process; in the other instance, some means of viewing the bottom must be provided and it is necessary to remove the container from the conveyor position for inspection, and then return it to the conveyor. Also, some inspections can be carried out while the container is rotating and others are best performed while the container is stopped.
Prior art devices are known for stopping the motion of a container in translation on a conveyor and for rotating it for inspection. These devices use moving cams or pairs of idlers, activated by air cylinders or solenoids, to push the containers against a rotating drive wheel or moving belt which then rotates the container for as long as the container is held in position against it by the idlers. When the idlers are pulled back, the container is released and can move forward on the conveyor belt.
The known devices have a number of disadvantages. One of these is that the rate at which containers can be handled is low. Accordingly, some machines are provided with more than one station, but this requires the use of an indexing device which is large and slow and utilizes considerable power in its operation. Most of these devices are synchronous and require a screw or star wheel infeed to assure proper positioning of the container. Also, such devices operate continuously, whether a container is present or not.
Desirably, the structure for stopping and rotating a container should be as uncomplicated as possible to provide for ease of manufacture and maintenance. The device should be passive, operating only when a container is present, and should be capable of accepting containers at present day production line rates. Lastly, the device should be easy to set up and to change for the many different sizes and shapes of containers that are characteristic of the product mix of present day container fabricators.